Behçet disease (BD) is associated with endothelial dysfunction and chronic inflammation. The neutrophil-lymphocyte (N/L) ratio and carotid intima-media thickness (cIMT) are markers of inflammation and vascular risk, respectively. We assessed the relationship between cIMT values and N/L ratio in BD (65 patients and 62 control participants). There were statistically significant differences in N/L ratios and cIMT values between the patients with BD and control group (P < .001). There were moderate positive correlations between cIMT value, C-reactive protein, and N/L ratio in patients with BD. Receiver-operating characteristic curve analysis suggested that the optimum N/L ratio cutoff point for patients with BD was 1.29, with a sensitivity, specificity, negative predictive value, and positive predictive value of 97, 77, 96, and 75%, respectively (area under curve: 0.691, 95% confidence interval = 0.600-0.782, P < .001). The N/L ratio may be a useful index of BD activity.